In some fluid delivery systems, such as, for example, those systems delivering hot melt adhesive or other thermoplastic materials, it is necessary to supply various output devices with predetermined volumes of the fluids. Metering pumps are utilized to in fact provide the fluids in metered amounts as required or dictated by means of their desired or specific end use. The metering pumps are driven by motor drive assemblies which operate the respective pumps at predetermined speeds in order that the metering pumps output the predetermined volumes of the fluid required for the particular use or by the particular output device. However, it is sometimes desired to achieve different metered fluid output volumes in order to provide different metered fluid output volumes to different output devices or for different end uses.
One known type of metering pump assembly is that disclosed within U.S. Pat. No. 6,688,498 which is entitled HOT MELT ADHESIVE SUPPLY SYSTEM WITH INDEPENDENT GEAR PUMP ASSEMBLIES and which issued to McGuffey on Feb. 10, 2004. While this metering pump system is quite satisfactory, it is noted that the arrangement does require the supply of the hot melt adhesive into a manifold and the subsequent supply or transmission of the fluid to the metering pump gears by means of a gearing system which comprises four gears. Another known type of metering pump assembly is that disclosed within U.S. Pat. No. 6,422,428 which is entitled SEGMENTED APPLICATOR FOR HOT MELT ADHESIVES OR OTHER THERMOPLASTIC MATERIALS and which issued to Allen et al. on Jul. 23, 2002. While this metering pump system is also satisfactory, it is noted that the drive shaft assembly and the fluid input into the metering pump assembly are not coaxially aligned with the longitudinal axis of the metering pump assembly. In addition, the different metering pumps or segments cannot be disposed or arranged such that their fluid output flows will be located at substantially the same predetermined positions within the metering pump assembly whereby the metered fluid output volumes from the various metering pumps or segments can effectively be added together so as to achieve additionally desired metered fluid output volumes which are different from that achieved from any single one metering pump or segment.
A need therefore exists for a new and improved metering pump or segment which is relatively simplified in structure and yet, when incorporated within a metering pump assembly, the individual metering pumps or segments can be driven by means of a single drive shaft assembly, the individual metering pump or segments can be fluidically connected together by means of a common fluid passageway, the individual metering pumps or segments can be interchanged with each other so as to provide different metered fluid output volumes at different predetermined locations, the metering pumps or segments incorporated within the metering pump assembly can be exchanged for other metering pumps or segments so as to provide still yet different metered fluid output volumes, and the metering pumps or segments incorporated within the metering pump assembly can be predeterminedly positioned with respect to each other such that the metered fluid output volumes from the various metering pumps or segments can effectively be added together so as to achieve additional different metered fluid output volumes.